1. Field of the Invention
The present invention pertains to wheeled, movable irrigation systems, and more particularly, it pertains to a rotary irrigation system which is arranged to be pivotally connected to a fixed water supply source and which is arranged to be moved in a circular path about the source to irrigate relatively large areas of land.
2. Description of the Prior Art
In those areas which receive little or no rainfall over extended periods of time, such as in the western portion of the United States, it is a common practice to water crops by means of movable irrigation systems. Typically, such irrigation systems comprise a string of interconnected pipe sections having sprinkler heads, or other water spreading means, arranged at spaced intervals along the length thereof and with support wheels being provided for the pipe sections at generally uniformly spaced intervals along the length thereof. The wheels may be arranged to support the pipe sections so that they pass through the axes of the wheels, or the wheels may be mounted on carriages for supporting the pipe sections at an offset position. In either case, the pipe sections and their associated sprinkler heads are supported at a fixed distance above the ground so that they will be above the crop which is to be irrigated. Some means is typically provided to move the string of pipe sections along the area to be sprinkled with the wheels rolling along in predetermined tracks. This movement can either be linear or it can be about a central pivot axis wherein an upstanding water supply pipe is located and to which one end of the pipe string is attached.
In the latter rotary arrangement, the interconnected string of pipe sections extends radially from the water supply pipe and is driven either by means of carriages which support the pipe sections at spaced intervals therealong or by means of a single power mover connected to the string of pipe sections at or near the outer end thereof, a typical example of the latter arrangement being shown in U.S. Pat. No. 2,536,261 to Van Den Brink. The motive power for such drive means may be provided by an electric battery, a gasoline driven engine, or through an electric power line running along the length of tubing and connected to an electric outlet at the inner, fixed end thereof. Alternatively, the drive means may be powered directly through the water pressure in the pipe sections.
In conventional prior art rotary irrigation arrangements, the drive means is geared to operate at a very slow rate so that the total area being irrigated will be provided with sufficient water and so that the string of pipe sections will make one complete revolution in the time normally required between waterings. This may typically be about eight days; hence, the entire string of pipe sections would be continuously driven at a slow rate so as to make one revolution about the central water supply pipe every eight days.